1. Field of the Invention
This invention relates to the field of electronic communication, and more specifically to secure communication between remote terminals via wire lines.
2. Description of the Prior Art
The encryption of electrically transmitted messages has long been considered important for many military, diplomatic and business situations. As a result, many types of enciphering devices are presently known, most of which utilize some type of key for converting the message into an encoded form. The source for the key may range in complexity from a simple codebook to a highly sophisticated deterministic key generator. A feature common to all known encryption systems is the necessity that each terminal in the communication link possess a common key in the form of a one-time pad, an initial key generator setting, or some similar commonly held starting point. Secure communication is thus complicated by the need to manually transfer, store and protect the key prior to its use in communication. Prior art key generators are further complicated by a need for precise synchronization of identical devices at each terminal, and by the requirement that key be provided in a manner determined by complex crypto-mathematical algorithms.
It is desirable to simultaneously, at two remote terminals, generate identical key suitable for protecting communications transmitted between the two terminals without the prior physical or electrical transmission of key variables between them and without the use of complex crypto-mathematical algorithms at either terminal.